A flow regulator is a device typically inserted in a natural gas pipeline which has a resilient plug expandable in the annular flow space to thereby control flow through the pipeline. Indeed, the resilient member can be expanded to the extent that all flow is closed off, the annular space being sealed by the expandable plug. Flow regulators of the present inventor are more specifically exemplified in U.S. Pat. Nos. 3,746,300, 4,351,510 and 4,442,999.
The present disclosure is directed to an improved feature above and beyond the structure of the previous flow regulators. By way of background, the flow regulator is constructed with a resilient plug which is compressed, causing swelling radially outwardly into the annular space. This is practically the only component to the apparatus which will ultimately wear out. The relatively high velocity gas flow past the plug causes the radial swelling to bunch or taper so that the back end of the resilient plug swells more than the front end of the plug. This creates stress concentration regions near the back end of the plug thereby resulting in failure at the back region of the plug. The above referenced patents disclose efforts at limiting this swelling as, for instance, by biased plies placed in the plug, or positioning a surrounding lip on the periphery of the plug at both ends.
While the improvements described in the foregoing patents have substantially extended the life of the resilient plug, the present disclosure is directed to yet another improvement which is thought to markedly extend the life of the resilient plug so that its life is substantially indefinite. The present disclosure is directed to a resilient plug which is confined at one end by means of a surrounding stress ring which is in the form of a segmented end cap or cover for the resilient plug having a peripheral lip or shoulder on the cylindrical outer wall of the plug. Moreover, this apparatus is a circular member which is cut with a plurality of radial lines to define multiple identical components which open up somewhat in the fashion of the petals of a flower. It has been determined that there is an optimum number of segments. While the number could increase substantially without limit, the optimum range is typically 36 segments or less, the preferred number of segments being 24 segments. Fewer segments will suffice, also, but as the number of segments is decreased, the gaps between adjacent segments tends to become larger. Accordingly, the range for the number of segments is about 8 to 36 segments with the optimum being 24 segments. The segments collectively define a solid member. The assembled segments is located so that it is able to expand as the plug is expanded outwardly which requires the segments to slide smoothly. They are normally confronted with a facing solid member which assists in squeezing the resilient plug, and to this end, the surface in contact with the end cap is preferably coated with a lubricated surface coating. That assists in sliding movement as the segments slide outwardly and are retracted inwardly on relaxation.
While the foregoing describes in general terms certain features of the present apparatus, the precise nature of the present invention is set forth in detail in the preferred embodiment described below.